Non-built light-duty liquid detergents compositions suitable for use in washing dishes are well-known. The term "dishes" refers to any utensils involved in food preparation and/or consumption which may be required to be washed to free the dishes from food particles and other food residues, greases, proteins, starches, gums, dyes, oils and burnt organic residues. Many such formulations in commercial use are based on a sulphonate-type anionic surfactants, such as linear alkylbenzene sulphonates for maximum biodegradability. Details on this type of product are taught in U.S. Pat. No. 4,537,709. However, powder based dishwashing products are generally not found. A powdered dishwashing product can have significant advantages in terms of economy of manufacture, shipping and use, as well as, environmental benefits through the elimination of plastic waste by utilizing natural container materials. The instant invention relates to a novel powdered dishwashing product having significant quantity of magnesium or calcium ions wherein these ions attack grease build-up which is a common problem in many dishwashing situations.
The use of magnesium or calcium ions to enhance detergent foam and detergency is taught in the patent literature and disclosed in U.S. Pat. Nos. 2,908,651, and 4,435,317, and British Patent Specifications 1,524,441 and 1,551,074. The art teaches that these formulations have enhanced performance, particularly when used in water of low mineral hardness. U.S. Pat. No. 4,482,268 discloses certain other advantages to using magnesium sulfate in the presence of nonionic-based powdered detergent formulations. Nevertheless the products made in accordance with these teachings have all been found to be non-optimum in various ways with respect to form, raw material expense, phase stability on storage, performance in water of varying hardness, harsh effect on hands and suds profile.
Accordingly, research has continued for compositions having improved economy, performance and in use characteristics and it has now been found that certain combinations of active ingredients can provide a range of enhanced properties not thought previously attainable in one formulation. More particularly it has been found possible to provide stable powdered dishwashing formulations of improved greasy soil removal, suds profile, and economy.
This invention relates to economical powdered form anionic surfactant based compositions, with significant levels of magnesium or calcium salts, formulated without the traditional powdered detergent addition of phosphate or silicate based builders, wherein the composition provides enhanced greasy soil removal and good suds profile. The improved detergency in powdered products with the addition of various phosphates and silicates, and borate builders is taught in U.S. Pat. No. 4,524,012. Phosphates have been shown to inactivate or sequester the polyvalent metal ions which cause water hardness. The effect of water hardness is obvious with soap based detergents in that precipitates are formed; and no lather is produced until the calcium and magnesium in the water have been removed as insoluble soaps--potentially as "bath-tub rings", or depositions in a fabric or other surface. It is further known that while synthetic detergents lather is not adversely affected by water hardness, there is an effect on their performance, especially in the washing of textiles.
The instant formulations which do not contain any builders are designed for conditions of low water hardness, where builders would not provide any enhanced benefit. Builders do not discriminate between the magnesium and calcium ions sourced from the water hardness vs. extra magnesium and calcium moieties added to the formulation to attack grease on dish surfaces. Hence, all magnesium and calcium moieties would be equally sequestered. Accordingly, the elimination of builders creates a more efficacious dishwashing product.
Further, it has been shown that solutions containing phosphate and silicate builders are cloudy in the presence of water hardness. By explicitly excluding any phosphate and/or builders a product with enhanced in-use cosmetic properties can be created.